1. Field of the Invention
The present invention relates to a side airbag device for a vehicle.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-240807 (JP 2011-240807 A) discloses a side airbag device for an automobile that includes a bag main body (side airbag) having two chambers of front and rear portions in which a front portion (front bag portion) and a rear portion (rear bag portion) are defined by a partition wall (front-rear partitioning section). The side airbag is configured to form a general V shape in a plan view by the front bag portion and the rear bag portion that can contacts with and applies pressure to an occupant in an oblique direction toward an approximate chest position of the occupant in an inflated and deployed state. This allows the upward curve of chest displacement to have a mild slope, the period required for the curve to reach the maximum value to be long, and the value to be low.
In such a side airbag as described above, the position of the front-rear partition section is determined in accordance with an inflation width of the rear bag portion in the vehicle fore-and-aft direction. Further, the inflation width of the rear bag portion in the vehicle fore-and-aft direction varies depending on an inflation width of the rear bag portion in the vehicle width direction. In other words, when gas is supplied into the rear bag portion, the pressure of the gas is uniformly applied to an inner surface of the rear bag portion. Therefore, when the inflation width of the rear bag portion in the vehicle width direction is changed, the inflation width of the rear bag portion in the vehicle fore-and-aft direction changes. In other words, the position of the front-rear partition section in the vehicle fore-and-aft direction varies. In order to prevent this circumstance, the degree of freedom in setting of the inflation width of the rear bag portion in the vehicle width direction has to be decreased. Accordingly, there is room for improvement in initial occupant restraining performance of the side airbag.